package com.chat.simplechat;

import java.util.*;

/**
 * @author wangyabin
 * @date 2022/11/8 13:59
 */
public class T {

    public static void main(String[] args) {
        Integer s = 25; //11001
        int y = 9;//1001
        System.out.println(s&y);
        Map<String,String> map = new HashMap<>(); 
        map.put("key","12");
        map.put("null","13");
        System.out.println(map.size());
        Set<String> set = map.keySet();
        Iterator iterator = set.iterator();
        while (iterator.hasNext()){
            System.out.println(iterator.next());
        }
        set.add("1");
        set.add("1");
        System.out.println(set.size());
    }
}
